A heat exchange ventilator includes: a partition wall that has a bypass opening allowing an exhaust air duct upstream of a total heat exchanger to communicate with the exhaust air duct between the total heat exchanger and a humidifier, and separates the exhaust air duct upstream of the total heat exchanger and a supply air duct downstream of the total heat exchanger; a bypass damper that opens and closes the bypass opening; and a controller that performs control to open the bypass opening by the bypass damper at a first time, and close the bypass opening by the bypass damper at a second time.